From: Bob Sinclair (bsinclair@netmasterclass.net)
Date: Fri Jun 11 2004 - 15:12:00 GMT-3
Alsontra,
The best discussion I have found on this topic is at the link below. The
short answer is, of course, it depends. Primarily on policed rate and TCP
Round-trip time.
The basic problem is that tcp traffic will back off each time a packet is
dropped, so we need to permit bursts above the desired rate in order to
actually approach it. Need to coordinate with the TCP windowing algorithm.
The 1.5 and 3 second rules are rough rules of thumb.
As far as the lab goes, if the policing burst values are not given, I would
not expect them to be critical in the grading.
Link:
http://www.cisco.com/warp/public/473/153.html
HTH,
Bob Sinclair
CCIE #10427, CISSP, MCSE
www.netmasterclass.net
----- Original Message -----
From: <alsontra@hotmail.com>
To: <ccielab@groupstudy.com>
Sent: Friday, June 11, 2004 10:28 AM
Subject: Two rate policer - bc/be calculation
> Command is as follows:
>
> "police cir 500000 bc 10000 pir 1000000 be 10000 conform-action transmit
> exceed-action set-prec-transmit 2 violate-action drop"
>
>
> I understand the utilization of the command, but I'm not sure how the bc
and
> be were calculated. I would think that the typical parameters would apply
and
> they don't:
>
> normal burst = configured rate * (1 byte)/(8 bits) * 1.5 seconds
> extended burst = 2 * normal burst
>
> cir 500000 ?
> bc 10000 ?
> be 10000 ?
>
> Or do the above calulations only apply to CAR? Anyone know the mathematics
> behind this?
>
>
> Additional info:
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t
> /122t4/ft2rtplc.htm
>
>
> TIA
> Alsontra
>
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